1. Field of the Invention
The present invention relates to an obstacle avoidance control system for a vehicle, wherein braking devices are automatically operated to avoid the contact of the vehicle with an obstacle, based on the relative positions of the vehicle and the obstacle detected by an obstacle detecting means such as a laser radar and the like.
2. Description of the Prior Art
Such an obstacle avoidance control system for a vehicle is already known, for example, from Japanese Patent Application Laid-open No. 7-21500. This obstacle avoidance control system is designed so that when a driver operates a steering wheel during an automatic braking operation to avoid the contact of the vehicle with the obstacle, braking forces for left and right wheels are individually controlled to generate a yaw moment, thereby assisting in the steering operation provided by the driver. The assisting in the steering operation is carried out, only when it is impossible to avoid the obstacle with the automatic braking operation only, due to a small distance between the vehicle and the obstacle.
In the above known system, when it is determined that it is possible to avoid the obstacle with the automatic braking operation only, the obstacle is avoided by recourse to the automatic braking operation only, without carrying-out a turnability increasing control operation which assists in the steering operation. However, it is very difficult to precisely determine whether it is possible to avoid the obstacle by the automatic braking operation, because the determination is governed largely by uncertain factors such as the friction coefficient of the road surface existing ahead of the vehicle and the like. Therefore, in the above known system, even when the obstacle can be avoided if the turnability increasing control operation assisting in the steering operation is carried out, there is the possibility of the generation of a situation in which the obstacle cannot be avoided with recourse to the automatic braking operation only.